In generic centrifugal casting methods the mold filling of the mold cavity in a hollow mold is based on the hollow mold being displaced around an axis of rotation in a rotational movement. As a result of this rotational movement, a corresponding centrifugal force acts on the liquid molten casting material during pouring in, pressing the casting material into the mold cavity and ensuring complete filling.
Depending on the density and heat capacity of the casting material, different rotation speeds are required for complete filling of the mold cavity. On the one hand, this is based on the fact that only a corresponding relatively weak centrifugal force acts on materials having a relatively low density, for example titanium, so that a correspondingly higher rotational speed must be selected to apply a sufficiently high filling force. In addition, materials having a low heat capacity such as titanium solidify relatively quickly so that complete filling of the mold cavity which requires sufficient flowability of the casting material must be accomplished in a very short time. A high rotational speed is again required for such short filling times.
In commercially available centrifugal casting apparatus for high-quality casting, such as those used for example in dental technology and jewelry manufacture, there is only one hollow mold which rotates at a certain distance about an axis of rotation located outside the hollow mold. From this it follows that considerable centrifugal forces act on the hollow mold itself. Thus, in order to keep the hollow mold on its rotational path in known centrifugal casting apparatus, solid mechanical superstructures are required to absorb the centrifugal forces and compensate for the imbalance produced by the rotating mass of the hollow mold and the mass of the casting material. The solid mechanical structure of known centrifugal casting apparatus results in a high weight with correspondingly high moments of inertia from which follow long acceleration or braking phases.
DE 195 05 689 A1 discloses a centrifugal casting apparatus with a reusable hollow mold in which mold cavities each of the same type are arranged in pairs such that they rotate about a common axis of rotation and can be filled through a common downgate. If more than two workpieces are to be cast at the same time using this known apparatus, the mold cavities each arranged in pairs are arranged one above the other in several layers so that they come to lie in several planes.
A disadvantage of this apparatus is that only an even number of workpieces of the same type can be produced in one centrifugal casting process. In addition, the overall height of the hollow mold varies as a function of the number of mold cavities provided together in the hollow mold so that, depending on the number of workpieces to be manufactured together in each casting process, different components are required for the superstructure of the centrifugal casting apparatus.